To repair hard tissue, particularly human and animal dental structures, such as tooth structures (e.g., dentin or enamel), first an adhesive is applied on the surface of the dental structure. Next, a restorative dental material may be applied on the adhesive, or the adhesive may be used alone without the restorative dental material, to repair or reconstruct the dental structure. Similarly, adhesives may also be used to bond dental materials (e.g., orthodontic appliances, generally utilizing an orthodontic adhesive) to a surface of a dental structure.
Various pretreatment processes can be used to promote the bonding of adhesives to dental structures such as dentin or enamel. Such pretreatment steps include etching, for example, using inorganic or organic acids, followed by priming to improve the bonding between the surface of the dental structure and the overlying adhesive. Following the etching and priming steps, an adhesive is applied and hardened to attach the dental restorative or orthodontic appliance. As a result, dental restoration procedures and the application of orthodontic appliances are typically multi-step processes.
Some “one-step” adhesives purport to provide etching, priming and adhering in a single step. However, a two step process is often carried out, including an initial application of water on the surface of the dental structure, followed by application of the adhesive and subsequent curing. Other “one step” primers are formed by mixing compartmentalized precursor ingredients such as, for example, water, adhesion monomers and an etchant, before they are applied on the dental structure surface.